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問題是,從美國開車回到加拿大, 順著公路出美國, 進加拿大, 不經過美國的 the port of entry.

隻經過加拿大的 the port of entry. There is no chance to talk to a US CBP officer at the port of Canadian entry.  加拿大入境一邊工作人員啥也不記錄. So I never have Canadian entry stamp on my Canadian passport. This happened many times.

-It does not matter for your dparture in this case, but when you re-enter US, youi need to go through the port of entry where the US CBP officer can inspect you. 

 咋辦?